Arrangement for the feeding of sheet-metal blanks to the drawing stage of a transfer press

ABSTRACT

An arrangement for the feeding of sheet-metal blanks to a first machine stage is provided. A drawing stage of a transfer press is provided which has a conveying device for taking sheet-metal blanks from a supply pile and depositing them in an intermediate depositing stage adjacent the supply pile. The conveying means takes the sheet-metal blanks from the intermediate depositing stage to a first machining stage adjacent the intermediate depositing stage. Transfer rails are provided which can be driven in transfer direction, in lifting in lowering direction and in closing and opening direction. Gripping devices are attached to the transfer rails for the transport of the workpieces between the machining stages. The intermediate depositing stage includes a first intermediate depositing station in front of the drawing stage developed as an aligning station for the sheet-metal blanks with respect to the first machining station and has one of fixed and movable stop devices for the alignment of the sheet-metal blanks in the direction of the passage through the press. The transfer rails are extended and can thus be guided into an area of the first intermediate depositing station and passive gripping devices provided for reaching under the sheet-metal blanks during the transfer and for the depositing of the sheet-metal blanks in a second intermediate depositing station. Active gripping devices which can grip the sheet-metal blanks irrespective of the movement of the transfer rails are provided for removing the sheet-metal blanks from the second intermediate depositing station, for the gripping, transport and depositing in the drawing stage.

This invention relates to an arrangement for the feeding of sheet-metalblanks to the first machining stage, especially to the drawing stage ofa transfer press, having conveying means for taking sheet-metal blanksfrom a supply pile and for depositing them in an intermediate depositingstation, for taking them from said intermediate depositing station andfor transporting and depositing them in the first machining station, andhaving transfer rails that can be driven in transfer direction, inlifting and lowering direction and in closing and opening direction andhaving gripping devices arranged at said transfer rails for thetransport of the workpieces between the machining stages.

The feeding of sheet-metal blanks to forming and reshaping tools intransfer presses today is fully automatic and as a rule requires onlymonitoring. Misrouting, such as a double-feeding of sheet-metal blanks,results in an early switching-off of the press or in the case ofpossible higher expenditures, during the supply in an ejection of thesheet-metal blank already in the feeding range witthout theswitching-off of the press. However, for reasons of cost, the additionalexpenditures are decreased at the expense of the utilization of thepress. In addition, in the case of transfer presses and especially thosefor large parts, a drawing stage is provided in the first machiningstage in order to avoid a turning of the large-surface parts. Thefeeding of the sheet-metal blanks in this case requires extremeprecision, means.

In DE-OS No. 29 00 526, a feeding arrangement for sheet-metal blanks tothe first stage of a transfer press is described having thecharacteristics of this type. The sheet-metal blanks, by means of thesuction lifting means of a vertical lifting mechanism, are taken fromthe supply pile, in the raised position are taken over by the suctioncups of a horizontal conveying means and are fed to the transfer press.The feeding is timed with the press and takes place in a motion that issynchronous with the transfer rails between the machining stages. Thisfeeding arrangement can only be used to a limited extent for transferpresses having a drawing stage as the first machining stage. Theorientation of the sheet-metal blanks on the basis of the supply pile isnot sufficient for a perfect depositing in the drawing tool, and it isnot ensured that the indicated orientation is maintained on thetransport route to the drawing stage.

In contrast, it is the objective of the invention to create anarrangement for the feeding of sheet-metal blanks to the first machiningstage of a transfer press, by means of which, in the course of thefeeding, the orienting of each sheet-metal blank takes place and ismaintained. In this case, special value is placed on the separation ofthe orienting movements. For the alignment of the sheet-metal blanks inthe direction of the passage through the press, the movement of thesheet-metal blank in this direction is to be utilized, and for analignment of the sheet-metal blanks transversely to the direction of thepassage through the press, the closing movement of the gripper rails isto be utilized.

In the case of arrangements of this type, the objective is achieved bythe fact that two intermediate depositing stations are provided beforethe drawing stage, of which the first intermediate depositing station isdeveloped as the aligning station for the sheet-metal blanks withrespect to the first machining station, having fixed and possiblymovable stopping means for the alignment of the sheet-metal blanks atleast in the direciton of the passage through the press, and that thetransfer rails are extended and can be guided into the area of the firstintermediate depositing station in this way and in it in each case havepassive gripping tools for reaching under the sheet-metal blanks duringthe transfer and for depositing said sheet-metal blanks in the secondintermediate depositing station, and active gripping tools for takingthe sheet-metal blanks out of the second intermediate depositing stationfor the purpose of gripping, conveying and depositing them in thedrawing stage.

By means of the arrangement according to the invention, the sheet-metalblanks are gripped in an advantageous manner before, with the movementof the formed workpeices in the individual machining stages, theunformed blank is deposited in the drawing tool.

After having been lifted off the supply pile, the sheet-metal blanks, bymeans of a destacking device, via for example a roller conveyor, can bebrought to conveying level and can be held in it. With the teaching ofthe conveying level, the first alignment of the sheet-metal blankspreferably takes place.

According to the invention the position of the sheet-metal blanks isadvantageously maintained that was adjusted in passage direction bymeans of aligning station and imprecisions occurring during the longoperation of the press are compensated. Irregularly shaped sheet-metalblanks, such as trapezoid sheet bars, can be gripped by the grippingtools of the transfer rails without loss of precision.

The advantageous suspending of the gripping tools by means according tothe invention ensures a high constancy of precision with a goodaccessibility of the gripping tools.

The foregoing and other objects, features, and advantages of the presentinvention will become more apparent from the following description whentaken in connection with the accompanyng drawings which show, for thepurposes of illustration only, one embodiment in accordance with thepresent invention, and wherein:

FIG. 1 is a simplified representation of the feeding arrangement with aview onto the conveying level of the sheet-metal blanks;

FIG. 2 is a partial section of a gripping tool fastened at a transferrail; and

FIG. 3 is a top view of the gripping tool according to FIG. 2.

Referring now to the drawings wherein like reference numerals are usedto designate like parts and more particularly to FIG. 1, wherein press 1is only suggested and shown in the area of the feeding of thesheet-metal blanks, witht he columns 2 and the bottom platen 3. Onetransfer rail 7 and 8 respectively extends on both sides of the tools 4and 6 in the the direction 49 of the passage through the press. Thetransfer rail 8 is shown in a return movement. No other bearing orsliding and guiding means are shown for the transfer rails 7, 8. Theadjusting possibility of the transfer rails in the opening and closingdirection 50 is indicated by means of the vertical rod 9, the adjustinghead 11 and the crossrods 12. The transfer rails, in addition can alsobe driven in transfer direction--which corresponds to the passagedirection 49 through the press--and in the lifting and loweringdirection 51. The machining stage 6 that is first in the direction ofthe passage through the press in this case is developed as a drawingstage, the second and each additional machining stage has the number 4and is used for a further shaping of the workpieces 31. The workpieces31, as sheet-metal blanks 28, 29, are fed to the press and via a firstconveying means 23 and possibly a second conveying means 24, are takenfrom supply piles 22 via suction lifting means 26, 27, are deposited ona roller conveyor or fed directly to a first intermediate depositingstation 17. Beyond the original length that has been required forreceiving the workpieces 31 from the first machining station 6 in orderto transport them to the next machining station 4 and deposit them inthe existing tool, the gripper rails are extended into the area of thefirst intermediate depositing station 17 and in it have passive grippingtools 13 which are described with respect to FIGS. 2 and 3. Thesheet-metal blank 28 which is deposited in the first intermediatedepositing station 17 on a flat plane which, for example, may be formedby the roller conveyor of the feeding device, is gripped with themovement of the transfer rails and deposited in a second intermediatedepositing station 18. In this position, the present sheet-metal blank29 can be gripped by means of active gripping tools 14 described, forexample, in DE-AS No. 18 02 630 and from this position, by means of themovement of the transfer rails 7, 8 can be deposited in the tool of thedrawing stage 6. Position 16 refers to other gripping tools required forthe transport of the workpieces. The first intermediate depositingstation 17 has spring-loaded stops 19 against which the sheet-metalblank 28 strikes when it first arrives. The return of the guidingmovement of these stops 19 results in the fact that the sheet-metalblank rests uniformly against the fixed stops 21. The movement of thespring-loaded stops 19 is shown schematically by double-headed arrows20. The sheet-metal blank is then aligned in passage direction 49through the press with respect to the drawing stage 6. In order to avoida sagging of the sheet-metal blank 28 during the transport from theintermediate depositing station 17 into the intermediate depositingstation 18, the roller conveyor may be extended beyond the secondintermediate depositing station 18. The position of a ferromagneticsheet-metal blank 29 may be secured here, for example, by magnetic means52. The alignment of the sheet-metal blank transversely to the direction49 of the passage through the press takes place by the closing movement50 of the transfer rails 7,8 where a resting takes place againstcorresponding stops mounted at the gripping devices 13. These stops areformed by the shaped parts 45, 46 as described in detail in FIGS. 2 and3.

FIGS. 2 and 3 show a passive grippng device 13 which is fastened at thetop side of the transfer rail 7 and 8. For this purpose, one--or asshown--two runners 32 rigidly mounted at the transfer rail are used, acarriage 34 that can be moved in passage direction (49) (FIG. 1) at saidrunners 32, a cross slide 36 disposed at said carriage 34 and slidablein transverse direction, a pressure plate 38 and only one spanner 39 andone clamping jaw 33. For purposes of adjustment, the gripping tool canbe adjusted by the loosening of the clamping jaw 39 in the direction ofthe passage through the press and transversely to it. For the transverseadjustability, the cross slide 36 has an oblong hole 37. The cross slide36 is extended by one or several brackets 40 which angular plates 41 areconnected via console plates 43. In the embodiment, two brackets 40 areconnected to the fixing means for receiving a gripping member. As afunction of the sheet-metal blank 28 (FIG. 1), other gripping membersmay be arranged at a fixing means. The angular plate 41 carries a baseplate 42 into which shaped pieces 45, 46 are inserted or shaped pieces45, 46 are placed onto said base plate 42. The shaped pieces 45, 46 inthis case are developed as cylindrical bolts which via bearing blocks 44are supported at the angular plate 41. The shaped pieces or cylindricalbolts 45, 46 are chamfered at 47 or, in these areas, have a strongdraft, for a besser entering of the sheet-metal blanks and in order toavoid tilting. In addition, FIG. 2 shows shaped pieces 45, 46 in alowered position with an end part of a sheet-metal blank 28 to bereceived.

Corresponding to FIG. 2, the shaped pieces 45, 46 have differentheights. The cylinder 45 projects over the cylinder 46 by an extent thatis identical to or larger than the thickest sheet-metal thickness to bemachined, such as that of a trapezoid sheet-metal blank 28. Theinterrupted line in FIG. 3 refers to the area of a trapezoid sheet-metalblank to be gripped by the gripping tool. The application 50 of thegripping tools 13 to the blank 28 takes place in the lowered position 51(FIG. 2) of the transfer rail 7, 8 in which case first only the shapedpiece 45 comes to rest against the sheet-metal blank 28. In the case ofthis motion, the alignment takes place in the direction of the arrow 50,thus transversely to the passage direction 49 through the press. Duringthe upward motion (lifting) of the transfer rails 7, 8, the shaped piece46 comes to rest against the edge of the sheet-metal blank 28.

While I have shown and described only one embodiment in accordance withthe present invention, it is understood that the same is not limitedthereto but is susceptible to numerous changes and modifications asknown to one having ordinary skill in the art and I therefore do notwish to be limited to the details shown and described herein, but intendto cover all such modifications as are encompassed by the scope of theappended claims.

I claim:
 1. An apparatus for the feeding of sheet-metal blankscomprising, at least one machining stage to which said sheet-metalblanks are fed, said at least one machining stage including at least afirst machining stage comprising a drawing stage of a transfer press, asupply pile from which said sheet-metal blanks are taken, anintermediate depositing stage adjacent said supply pile, conveying meansfor taking sheet-metal blanks from said supply pile and for depositingthem in the intermediate depositing stage adjacent said supply pile, fortaking them from said intermediate depositing stage and for transportingand depositing them in the first machining stage adjacent saidintermediate depositing stage, and having transfer rails that can bedriven in transfer direction, in lifting and lowering direction and inclosing and opening direction, and having gripping devices attached tosaid transfer rails for the transport of the workpieces to and betweenthe at least one machining stage,said intermediate depositing stageincluding a first intermediate depositing station in front of the firstmachining stage being developed as an aligning station for thesheet-metal blanks with respect to the first machining stage and havingone of fixed and movable stop means for the alignment of the sheet-metalblanks at least in the direction of the passage through the press, andwherein the transfer rails are extended and can thus be guided into anarea of the first intermediate depositing station, said intermediatedepositing stage further including a second intermediate depositionstation, and passive gripping means for reaching under the sheet-metalblanks during the transfer and for depositing said sheet-metal blanks insaid second intermediate depositing station, and active gripping meansfor gripping said sheet-metal blanks irrespective of the movement ofsaid transfer rails and for removing the sheet-metal blanks from saidsecond intermediate depositing station, for the gripping, transport anddepositing in the first machining stage.
 2. An arrangement according toclaim 1, wherein the passive gripping means, in addition to onerespective bearing surface, also have first shaped pieces against whichthe sheet-metal blanks rest in the direction of the passage of theworkpieces through the transfer press, and second shaped pieces againstwhich the sheet-metal blanks rest during the closing movement of thetransfer rails.
 3. An arrangement according to claim 2, wherein thefirst and second shaped pieces are cylindrical bolts disposed in thebase plate via bearing blocks at an angular plate.
 4. An arrangementaccording to claim 2, wherein the first and second shaped pieces havedrafts for the entering of the sheet-metal blanks in the passivegripping means.
 5. An arrangement according to claim 2, wherein thefirst shaped pieces of the passive gripping means for the transversealignment project over the second shaped pieces for the longitudinalalignment.
 6. An arrangment according to claim 1, wherein the passivegripping means, via a fixing arrangement, are mounted at the transferrails so that the passive gripping means can be adjusted and fixed inthe direction of the passage through the press and substantiallytransversely to that direction.
 7. An arrangement according to claim 6,wherein the fixing arrangment has at least one runner fastened at atleast one of said transfer rails, said runner extending in the directionof the longitudinal extension of said one transfer rail, a carriageslidably arranged in said one transfer rail, a cross slide directedtransversely to the runner, said cross slide being disposed at thecarriage so that it can be moved substantially transverse to the runnerfor receiving the passive gripping means and clamping means for thejoint arresting of the cross slide and the carriage at the runner.
 8. Anarrangement according to claim 1, further comprisingholding meansdisposed in the area of the second intermediate depositing station atconveying level, aligned corresponding to the shape of the sheet-metalblank.
 9. An arrangement according to claim 3, wherein the first andsecond shaped pieces have drafts for the entering of the sheet-metalblanks in the passive gripping means.
 10. An arrangement according toclaim 3 wherein the first shaped pieces of the passive gripping meansfor the transverse alignment project over the second shaped pieces forthe longitudinal alignment.